ABSTRACT
While droughts predominantly induce immediate reductions in plant carbon uptake, they can also exert long-lasting effects on carbon fluxes through associated changes in leaf area, soil carbon, etc. Among other mechanisms, shifts in carbon allocation due to water stress can contribute to the legacy effects of drought on carbon fluxes. However, the magnitude and impact of these allocation shifts on carbon fluxes and pools remain poorly understood. Using data from a wet tropical flux tower site in French Guiana, we demonstrate that drought-induced carbon allocation shifts can be reliably inferred by assimilating Net Biosphere Exchange (NBE) and other observations within the CARbon DAta MOdel fraMework. This model-data fusion system allows inference of optimized carbon and water cycle parameters and states from multiple observational data streams. We then examined how these inferred shifts affected the duration and magnitude of drought's impact on NBE during and after the extreme event. Compared to a static allocation scheme analogous to those typically implemented in land surface models, dynamic allocation reduced average carbon uptake during drought recovery by a factor of 2.8. Additionally, the dynamic model extended the average recovery time by 5 months. The inferred allocation shifts influenced the post-drought period by altering foliage and fine root pools, which in turn modulated gross primary productivity and heterotrophic respiration for up to a decade. These changes can create a bust-boom cycle where carbon uptake is enhanced some years after a drought, compared to what would have occurred under drought-free conditions. Overall, allocation shifts accounted for 65% [45%-75%] of drought legacy effects in modeled NBE. In summary, drought-induced carbon allocation shifts can play a substantial role in the enduring influence of drought on cumulative land-atmosphere CO2 exchanges and should be accounted for in ecosystem models.
Subject(s)
Carbon Cycle , Droughts , Tropical Climate , French Guiana , Forests , Carbon/metabolism , Models, TheoreticalABSTRACT
The improvement of agricultural TFP is critical to promoting the high-quality development of agriculture. This paper described and identified the spatiotemporal differentiation characteristics and spatial correlation of China's agricultural TFP in 283 prefecture-level cities from 2001 to 2018 using the Metafroniter-Malmquist and Moran index. The results showed that: (1) From 2001 to 2018, China's agricultural TFP was 6.64%, and its growth was mainly driven by agricultural technological progress. The contribution of agricultural technological efficiency was small. The growth law showed an "inverted U-shaped" growth trend of first rising and then falling. (2) China's agricultural TFP has significant characteristics of regional unbalanced growth. (3) The growth rate of agricultural TFP in most prefecture-level cities is medium and slow, and most prefecture-level cities relied on agricultural technological progress to promote growth. (4) The agricultural TFP of various cities showed a significant spatial correlation phenomenon of "high-high" or "low-low." This study has significant theoretical and practical value for maintaining the stable growth of China's agricultural TFP and promoting the high-quality development of China's agriculture.
A melhoria do TFP agrícola é fundamental para promover o desenvolvimento de alta qualidade da agricultura. Este artigo descreve e identifica as características de diferenciação espaço-temporal e a correlação espacial do TFP agrícola chinês em 283 cidades de nível de prefeitura, de 2001 a 2018, usando os índices Metafroniter-Malmquist e Moran. Os resultados mostram que: (1) De 2001 a 2018, o TFP agrícola da China foi de 6,64%, e seu crescimento foi impulsionado principalmente pelo progresso tecnológico agrícola. A contribuição da eficiência tecnológica agrícola foi pequena. A lei de crescimento mostrou uma tendência de crescimento "em forma de U invertido" de primeiro aumento e depois queda. (2) O TFP agrícola chinês apresenta características significativas de crescimento desequilibrado regional. (3) A taxa de crescimento do TFP agrícola na maioria das cidades de nível de prefeitura é média e lenta, e a maioria das cidades de nível de prefeitura depende do progresso tecnológico agrícola para promover o crescimento. (4) O TFP agrícola de várias cidades apresentou um fenômeno de correlação espacial significativo de "alto-alto" ou "baixo-baixo". Este estudo tem valor teórico e prático significativo para manter o crescimento estável do TFP agrícola da China e promover o desenvolvimento de alta qualidade da agricultura da China.
Subject(s)
Agriculture , Correlation of Data , Government Agencies , ChinaABSTRACT
ABSTRACT: The improvement of agricultural TFP is critical to promoting the high-quality development of agriculture. This paper described and identified the spatiotemporal differentiation characteristics and spatial correlation of China's agricultural TFP in 283 prefecture-level cities from 2001 to 2018 using the Metafroniter-Malmquist and Moran index. The results showed that: (1) From 2001 to 2018, China's agricultural TFP was 6.64%, and its growth was mainly driven by agricultural technological progress. The contribution of agricultural technological efficiency was small. The growth law showed an "inverted U-shaped" growth trend of first rising and then falling. (2) China's agricultural TFP has significant characteristics of regional unbalanced growth. (3) The growth rate of agricultural TFP in most prefecture-level cities is medium and slow, and most prefecture-level cities relied on agricultural technological progress to promote growth. (4) The agricultural TFP of various cities showed a significant spatial correlation phenomenon of "high-high" or "low-low." This study has significant theoretical and practical value for maintaining the stable growth of China's agricultural TFP and promoting the high-quality development of China's agriculture.
RESUMO: A melhoria do TFP agrícola é fundamental para promover o desenvolvimento de alta qualidade da agricultura. Este artigo descreve e identifica as características de diferenciação espaço-temporal e a correlação espacial do TFP agrícola chinês em 283 cidades de nível de prefeitura, de 2001 a 2018, usando os índices Metafroniter-Malmquist e Moran. Os resultados mostram que: (1) De 2001 a 2018, o TFP agrícola da China foi de 6,64%, e seu crescimento foi impulsionado principalmente pelo progresso tecnológico agrícola. A contribuição da eficiência tecnológica agrícola foi pequena. A lei de crescimento mostrou uma tendência de crescimento "em forma de U invertido" de primeiro aumento e depois queda. (2) O TFP agrícola chinês apresenta características significativas de crescimento desequilibrado regional. (3) A taxa de crescimento do TFP agrícola na maioria das cidades de nível de prefeitura é média e lenta, e a maioria das cidades de nível de prefeitura depende do progresso tecnológico agrícola para promover o crescimento. (4) O TFP agrícola de várias cidades apresentou um fenômeno de correlação espacial significativo de "alto-alto" ou "baixo-baixo". Este estudo tem valor teórico e prático significativo para manter o crescimento estável do TFP agrícola da China e promover o desenvolvimento de alta qualidade da agricultura da China.
ABSTRACT
As a key precursor of vitamin C, 2-keto-L-gulonic acid (2-KLG) was mainly produced from L-sorbose by mixed fermentation of Ketogulonicigenium vulgare and a helper strain (Bacillus spp.) with a low conversion rate for decades. The aim of this study was to enhance the 2-KLG production by co-culturing K. vulgare and Bacillus megaterium using three-stage temperature control (TSTC) strategy. By investigating the temperature effect on the 2-KLG fermentation, the optimum temperatures for the growths of K. vulgare and B. megaterium were 32 °C and 29 °C, respectively, while the optimum temperature for 2-KLG production was 35 °C. We developed a TSTC process: the temperature was kept at 32 °C during the first 16 h of fermentation, then decreased to 29 °C for the following 14 h, and maintained at 35 °C to the end of fermentation. By using this new process, the productivity and yield of 2-KLG from L-sorbose were obtained at 2.19 ± 0.19 g/L/h and 92.91 ± 1.02 g/L in 20-L fermentors for 5 batches, respectively, which were 22.35% and 6.02% higher than that of the control treatment (the single temperature of 29 °C). The increased cell density of K. vulgare during the exponential phase and the enhanced SDH activity (increased by 25.18% at 36 h, 17.14% at 44 h) in the production stage might be the reasons for enhanced 2-KLG conversion rate and yield. Our results demonstrated the feasibility of the TSTC strategy for 2-KLG production.